SCOTTISH singing sen sation Susan Boyle says all the attention suddenly lavished on her last spring was like being hit with a “giant demolition ball.”

“Anyone who has that kind of impact — finds it really hard to get a head around it,” Boyle says on tomorrow’s “Today” show — her first sitdown US TV interview since rocketing to stardom on “Britain’s Got Talent.”

In the interview, conducted by Meredith Vieira last week in LA, a made-over Boyle talks about the impact her international fame had on her psyche.

The day after the “BGT” finale, runner-up Boyle — who’d been exhibiting very public signs of stress — was admitted to The Priory, a private mental health facility in London, suffering from anxiety.

She also missed several performances during the “BGT” concert tour, which kicked off after the show ended.

“I’ve got to be honest here,” Boyle says. “I guess I had to get my head around it, but through the guidance of a great team, and they are very good, I was able to see that in perspective and really turn that around a little.”

The previously unknown Boyle, 48, became a sensation after YouTube clips of her singing “I Dreamed a Dream” from “Les Miserables” and “Memory” from “Cats” — during her “BGT” audition –were watched over 200 million times.

It created a firestorm of media attention around the unassuming Boyle, who lives alone with her cat, Pebbles, and who appeared ill-prepared to handle her sudden fame.

Boyle tells Vieira that “being plucked from obscurity is a bit like, you know, going on a long journey.